Apparatus for shaping hollow objects



Oct. 6, 1964 M. M. GARVIN APPARATUS FOR SHAPING HOLLOW OBJECTS 5 Sheets-Sheet 1 Filed April 3, 1961 INVENTOR. MILTON M. GARY/IV ATTORNEYS Oct. 6, 1964 Filed April 5, 1961 SELECTOR M. M. GARVIN APPARATUS FOR SHAPING HOLLOW OBJECTS 3 Sheets-Sheet 3 MM To #4. GAEW/V- L dia,

ATTORNEYS United States Patent 3,151,590 APPARATUS FOR SHAPKNG HGLLGW OBJECTS Milton M. Garvin, Cincinnati, Ohio, assignor, by mesne assignments, to American Radiator & Standard Sanitary Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 3, 1961, Ser. No. 160,324 Claims. (Cl. 11344) This invention relates to an hydraulic system, more particularly to an automatic cyling system for the control and operation of hydraulic apparatus employing a plurality of operating means.

It is a general object of the present invention to provide a novel and improved hydraulic system including automatic control means for causing and controlling the operation of a plurality of operating means sequentially and cyclically.

More particularly, it is an object of the invention to provide an improved apparatus for forming a hollow member to a desired shape in a die cavity by subjecting the interior of the hollow member to a fluid pressure of sufficient magnitude to cause the hollow member to deform and conform to the shape of said cavity.

I am aware that heretofore, devices, apparatus, systems, etc., are known for producing hollow members by subjecting a hollow blank to internal forces and thereby causing it to be shaped by plastic deformation to conform to the shape of a cavity provided in a die. While certain devices, apparatus, and systems of this type have been constructed and employed with some degree of success, in general, it has been necessary to provide in conjunction with such means, elaborate controls for correlating forming pressures and the rate of fiow of the material of which such formed members are comprised, particularly in those instances where the ultimate shape of the member is complicated and/or a substantial flow of material occurs during the forming operations. Such elaborate controls and provisions necessarily result in apparatus which is quite complicated and also expensive. Accordingly, one of the principal objects of the present invention is the provision of apparatus for forming hollow members to a desired shape more economically than by previously known apparatus and which is relatively simple and economical.

Another and more specific object is in the provision of apparatus which is particularly adapted for use as starting material for hollow blanks made from standard commercial tubing and requiring no special preforming treatment except the cutting of proper lengths from longer lengths of commercial tubing and in which the need for special feed control means is eliminated through the use of balanced and opposed fluid pressures during a forming operation.

Another object is in the provision of forming apparatus which is improved through the simplification of previously known devices, examples of which being illustrated and described in Gray et al. Patent 2,203,868, Leuthesser et el. Patent 2,713,314, Stephens Patent 2,407,855, Garvin Patent 2,902,962, Shoemaker Patent 2,331,430, and others.

In general, the present invention contemplates means for forming a hollow workpiece by the introduction into and ateach opposed end thereof fluid under pressure sufficient to shape the workpiece to a cavity provided in the mold or die in which the workpiece is secured, thereby greatly simplifying means for containing the fluid under the high pressures necessary for such forming, and eliminating the need for correlating and controlling the rate of feed of the material of the workpiece in reference to the forming pressure.

Other objects and advantages will be apparent to those skilled in .the art from the following description taken in' connection with the accompanying drawings in which:

FIG. 1 is a schematic plan diagram of the apparatus;

FIG. 2 is a diagrammatic view illustrating hydraulic connections between various components of the apparatus; and

FIG. 3 is a wiring diagram.

In FIG. 1 of the drawings, a machine 1 is illustrated in which a hollow tubular member or workpiece 2 is shaped to the contour of a cavity provided in a die 3. A fixed volume of fluid is supplied to the interior of the workpiece 2 while it is held firmly secured within the die 3 following which pressure is applied to the fluid of suthciently intensity to cause the workpiece to be shaped according to a cavity provided in die 3.

The machine comprises a base having a relatively heavy rigid stationary platen 4 on which the bottom half 5 of die 3 is mounted. The machine also includes a toggle press portion 6 to which the upper half 7 of die 3 is firmly secured.

Operating means in the form of a cylinder 8, piston 9 having a piston rod 10 connected to toggle press 6 are provided for raising and lowering die half 7 and also for withstanding the hydraulic pressures supplied to the workpiece during the forming operation. Operation and control of press cylinder 8 and its associated piston 9 is elfected by means of a pump 11 and a valve 12 for directing fluid supplied by pump 11 through conduit 13 to said valve either to the upper or lower portion of cylinder 8 through conduits 14- or 15, as the case may be, by means of solenoids 16, 17. Solenoids l6 and 17 are selectively energized or deenergized at a given time so as to direct flow from pump 11 to the upper portion of cylinder 8 and simultaneously permit drainage of hydraulic fluid from the lower portion of cylinder 8, or vice versa.

As illustrated in FIG. 1, a workpiece 2 shaped in the form of a T is shown by way of example only. It will be understood that a given die 3 will have an opening corresponding to one particular workpiece to be formed. When it is desired to form a workpiece having a different shape, a different set of dies having a cavity therein corresponding to said different type of workpiece will be employed.

In addition to the above-mentioned cavity (not indicated by a reference numeral), each half of die 3, that is lower half 5 and upper half 7 is provided with passageways 18, 19, extending from an appropriate side of each of said respective die halves through interior portions of said halves and each terminates at opposed and portions of the above-mentioned cavity having the shape of a desired workpiece.

The purpose of passageways 18, 19 is to receive hollow tubular seals which are advanced to engage a workpiece 2 within the die at a suitable time during the operation of the machine and when press 6 is down with die halves 5 and 7 together or in closed position. At other times during the operation and with the die closed, hollow tubular seals 20, 21 are retracted.

As illustrated in FIG. 1, seals 20, 21 are shown advanced, in which condition, their respective ends are in engagement with workpiece 2.

The hollow tubular seals 20, 21 are connected to pistons 22, 23, respectively, said pistons being adapted to reciprocate in cylinders 24, 25 respectively.

As noted heretofore, seals 20 and 21 are each of a hollow tubular type of structure with the hollow portions Zila, 21a of each seal extending completely therethrough; Each of said seals has an end portion 20b and 2115, respectively, for engaging workpiece 2 and is provided with a port 26, 27 respectively, adjacent the end portion thereof which are opposite the work-engaging end portion. Thus,

with the seals engaging the workpiece, which is also hollow, there is provided an hydraulic circuit through which fluid may be suppliedto and from both seals and the workpiece. As indicated in FIG. 2, water or other fluid is supplied to such hydraulic circuit by means of a pump 23, conduit 29 and a flexible connection 39 connected to port 27. Water so supplied then flows through the hollow portion of seal 21, through the interior of workpiece 2 (indicated by the dotted line in FIG. 2), then through the hollow portion of seal 29 and out through port 26 thereof.

Hydraulic fluid is supplied to cylinders 24 and 25 by means of pump unit 31, flow directing valve 32, and connecting conduits 34 and 35. Valve 32 has ,two solenoids 36, 37, either of which is selectively energized so as to simultaneously admit fluid to and simultaneously drain piece 2 and simultaneously increasing the pressure of said trapped fluid. Such means includes a pair of cylin-' ders 38, 39 having therein pistons 40, 41, respectively. Connected to piston 4t) is a piston rod 42 which is coaXially aligned with the longitudinal axis of hollow tubular seal 20. 'Rod 42 has an end 43 disposed within the hollow portion 29a of tubular seal 20. As illustrated in FIGS. 1 and 2, piston 49 is in its fully retracted position and seal 20 is in its advanced position in engagement with workpiece 2. With seal 20 and piston 40 so disposed, the end 43 of rod 42 is immediately adjacent port 26. Hence, a very slight amount of advance movement of piston 49 produces a corresponding movement of end 43 thereby closing off port 26 since rod '42 is closely fitted within the hollow bore 25a of seal 20. Similarly, a rod 44 having an end 45 is connected to piston 41. With piston 41 fully retracted, the end 45 is within the hollow .bore 21a of seal 21 and is immediately adjacent port 27"when seal 21 is advanced and in engagement with workpiece 2. Hence, a very slight advance movement of piston 41 results in end 45 cutting off or closing off port 27 in a similar manner to that described in connection with end 43 and port 26.

Movement of pistons 40, 41 is effected by means of hydraulic fluid under pressure supplied by a pump 46, conduit 47, flow directing valve 48 and conduits 49, 49a, 49b, and 50, 50a and 5%. Valve 48 is provided with solenoids 51, 52 so that the hydraulic fiuid under pressure may be selectively directed either to the upper or lower sides of pistons 40 and 41 and simultaneously draina closed simultaneously upon advancing movement of said pistons. V

Referring now to the wiring diagram, FIG. 3,'lines 53, 53a are connected, or are adaptedto be connected to a a suitable source of voltage. A switch having contacts '54,. 55, a is provided for selectively controlling each individual step in the operation of the machine manually" or automatically, The present discussion will be concerned only with the automaticaspects of operation and control and hence it will be assumed that connection is V established between contacts 54 and 55 so that relay CR-2 is energized by line 56'. 'When relay CR-2 is energized, the machine and its control'circuit is then in com ,ditionsothat its operating cycle can be commenced and controlled automatically.

' best illustrated in FIG. 2.

cycle is commenced. When both palm buttons 57, 58

are depressed, this completes a circuit to energize relay CR4 by means of lines 59, palm buttons 57 and '58, line 69, normally closed contacts 61 of relay CR5 and line 62. When this is accomplished, normally open contacts 63 of relay CR-4 become closed thereby completing a circuit through line 64 to energize solenoid 17 of valve 12. When solenoid 17 is energized, hydraulic fluid is supplied under pressure by pump 11 and is directed through conduit 13 and valve 12 and then to the upper side of piston 9 by means of conduit 14 thereby causing press 6 to descend and ultimately close die 3 in which a workpiece 2 has been previously placed.

Limit switches LS1 and LS2 are mounted on the machine in such a position that'both limit switches are closed when die 3 is fuhy closed. Limit switches LS-l and LS-Z, are connected in series and in the circuit that energizes relay CR-6 to insure that die 3 is fully closed before any movement of seals 20, 21 takes place. Relay CR- controls the positioning of the seals and is energized by a circuit which is completed upon closure of LS-1 and LS2 and which includes line 59,-series connected limit switches LS-l and LS-2, normally open contacts 63, '54 of relay CR2,normally closed contacts 65 of relay CR5, and line 66. 1

With relay CR-6 now energized, its normally open contacts 67 together with line 68 complete a circuit which energizes solenoid 37 of valve 32, thereby supplying hydraulic fluid under pressure from pump 31 through valve 32 and conduit 33 to the lower side of pistons 22, 23 thus causing seals 20, 21 to advance and engage the Workpiece. As noted heretofore, conduit 34 supplies hydraulic pressure to both seal cylinders 24, 25 simultaneously, thus causing both seals 20, 21 to advance simultaneously.

When seals 20, 21 engage the workpiece, this provides resistance against further movement and hence causes the pressure in seal cylinders 24, 25 and in conduit 34 to increase.v When the seal cylinder pressure has increased to a preselected value, a pressure switch PS4 is actuated so that its contacts 69, 70 then become closed thereby completing an energizing circuit which energizes and starts timer TR-2. Simultaneously, solenoid 71 is energized by means of another circuit connected in series with contacts 69, 70 of pressure switch PS-l and in parallel with timer TR-Z. This parallel circuit includes normally closed contacts 72 of timer Tit-2 and normally closed contacts 73 of relay CR-7. When solenoid 71 has been energized, water or other fluid is then supplied by pump 28 through conduits 29, 30 and inlet port 27 to the hollow bore portion 21a of seal 21. Sinceseals 20, 21 are then in engagement with the hollow workpiece 2, the water flows from 7 seal 21 through the workpiece, then through the hollow bore 20a of seal 20, and finally out Means are provided for trapping and simultaneously applying pressure to a definite volume of fluid within the hollow bores 20a 21a of seals 29, 21 and the workpiece 2, said pressure being of sufiicient magnitude to form the workpiece and cause it to be shapedrto conform to the contour of the cavity provided in die 3.

- The time cycle of timer TR-2 provides suihcient time" for'pump 28 to completely fill the holloWport-ions of seals 20, 21 and workpiece 2, as above noted. Upon com.- pletion of the time cycle, the normally open contacts 74 or timer TR 2 become closed to energize relay CR-7 through a circuit which includes contacts 74, normally open contacts 75 of relay CR-2, line 76.--and normally The cycle is commenced when an operator depresses both palm buttons 57, 58 which are physically spaced apart on the control panel otthe machine and series 'con-. nected electrically in order to insure that both hands of an operator 'are'clear of the pressbefore fan operating .clo'sed contacts 77 of relay CR-S. When relay CR- 7 is energized, its normally open contacts 7S completea cir-,

cuit through line 79'to energize solenoid 52 of valve 48.

When. solenoid 52 is energized, hydraulic fluid. under pressure is suppliedbypump unit 46 to bothforming cylinders 38, 39 simultaneously through conduit 49 and through port 26, as is by simultaneously closing otf ports 25 and 27 and, hence, trap within the hollow seals 20, 21 and workpiece 2, a definite volume of fluid, the pressure of which is increased by the continued advance of pistons 40, 41. As these pistons continue to advance, sufficient pressure is imparted to said volume of trapped fluid to cause deformation of the walls of the hollow workpiece 2 and thus cause it to be shaped to conform to the cavity provided in die 3.

As the pressure is thus built up within the workpiece there is necessarily a simultaneous build up of pressure in cylinders 38, 39, and, hence, in conduit 49. When the pressure in conduit 49 reaches a preselected value, pressure switch PS2 is actuated which results in the closing of its contacts 80, 81, and the completion of a ch'cuit to energize relay CR-S through line 82. When contacts 8%, 81 close, CR5 becomes energized thus causing both sets of its normally closed contacts 61 and 65 to open and thus de-energize relays CR4 and CR6 which in turn deenergizes solenoids 17 and 37 of valves 12 and 32, respectively. Simultaneously with the closing of contacts 8%, 81 of pressure switch PS2, the normally open contacts 83, 84 of relay CR5 become closed, thereby energizing relay (IR-8 through line 85. Also simultaneously with the closing of pressure switch PS-Z contacts 89, 81 and the resulting energization of relay CR-S, another set of normally open contacts 86 of the latter relay become closed thereby resulting in relay CR9 becoming energized by a circuit which includes line 59, series-connected limit switches LS1 and LS-2, normally open contacts 63 of relay CR-Z, normally open contacts 36 of relay CR5, normally closed contacts 87 of relay CRo' and line 83. As noted above, when relay CR5 becomes energized, this results in relay CR4 becoming ole-energized, thereby causing its normally closed contacts 39 to close and energize relay CR-3 by means of a circuit which includes cries-connected normally closed contacts 89 of relay CR4, normally open contacts 90 of relay CR4, and line 91.

As noted above, when relay CR-S becomes energized, in addition to the de-energizing of relays CR- and CR-6, this results in the energizing of relays CR-S, (ZR-9, and CR3. When CR3 becomes energized, its normally open contacts 92 become closed thereby energizing solenoid 51 through line 93. Simultaneously, normally closed contacts 77 of relay CR8 are opened thereby deenergizing relay CR-7 which in turn causes its normally open cotnacts 7 8 to again become open thus de-energizing solenoid 52. As noted above, the relationship of conduits 49 and 59 is reversed in respect of pump 44 so that hydraulic fluid supplied under pressure is now supplied by pump 44 to the upper portions of cylinders 38, 39, and, simultaneously, fluid from the lower portions of these cylinders is returned to a suitable sump through conduit 49. Hence, when relay CR-8 is energized, pistons 4t), 41 are caused to retract to their initial positions.

When relay CR9 becomes energized, its normally open contacts 94 become closed which results in solenoid 36 becoming energized by line 95. Also, as noted above, relay CR6 becomes de-energized in response to the preselected value of forming pressure and, hence, its normaliy open contacts 67 interrupt the circuit heretofore completed through line 68 to de-energize solenoid 37. Accordingly, the relationship of conduits 34, 35 in respect of pump 31 becomes reversed so that the latter pump now supplies hydraulic fluid under pressure to the upper portions of seal cylinders 24, 25, through conduit 35 and simultaneously allows fluid to bedrained from the lower portion of said cylinders through conduit 34. Hence, when relay CR-9 becomes energized, this causes seals 20, 21 to be retracted away from the workpiece and returned to their initial positions. Similarly, when relay CR-3 becomes energized, this results in solenoid 16 becoming energized and solenoid 17 becoming de-energized. Hence, the relationship of conduits 14, 15, in respect of pump 11 is reversed to retract the press 6 and open die 3. This is accomplished by closing of normally open contacts 96 of relay CR-3 when that relay becomes energized, thereby completing a circuit through line 97 to energize solenoid 16. When this occurs, relay CR4 has become de-energized which results in its normally open contacts 63 again becoming open, thus interrupting the circuit through line 64 and solenoid 17 becoming deenergized.

It will be noted that timer TR-l is connected in parallel with relay CR8 so that this timer becomes energized simultaneously with relay (JR-8. Timer TR1 has a set of normally open contacts 98 which together with line 99 form a holding circuit for relay CR-S, normally open contacts 84 of relay CR-S, line 85, timer contacts 98, and line 99 forming this holding circuit. As noted above, contacts 98 are normally open and become closed when the timer is energized. Contacts 98 remain closed until the timer completes its timing cycle, thereby insuring enough time for the completion of all of the above events following the energizing of relay CR-S. Upon completion of said cycle, contacts 98 again open to interrupt the holding circuit for relays CR-S and CR-S as well as timer TR-l. Such provision avoids premature de-energization of relay CR5 and the opening of its contacts 80, 81 which might result from a rapid decrease of pressure in conuit 49 upon reversal of the relationship of conduits 49, 59 in respect of pump 46. Upon completion of the above sequence of operations, the cycle is completed and all control elements as well as the elements of the machine have returned to their initial position and/ or condition. Upon completion of the cycle, an operator removes the formed workpiece from die 3, inserts a new workpiece for the next forming operation which is initiated by again depressing both palm buttons 57, 58.

The wiring diagram shown in FIG. 3 may be operated entirely by manual manipulation by placing the selector switch in manual position, that is, with connection established between contacts 54 and a. In such position, the mold down switch may be actuated to bring the mold down since the placing of the selector switch in the manual position energizes relay CR-1 thereby closing its normally open contacts 1.00. Thus, when an operator actuates the mold down switch, relay CR4 is energized which causes press 6 to descend and ultimately close die 3 as noted above.

Next, the seals in button is closed thereby energizing relay CR-6 because relay CR-l is energized and hence its contacts 101 are then closed. Once relay CR-6 is thus energized, its contacts 162 then close to complete a holding circuit with normally closed contacts 103 of relay CR-9, said holding circuit being parallel-connected with the seals in button. As noted above, when relay CR-6 is energized, seals 29, 21 advance and sealingly engage the open opposed ends of workpiece 2. After seals 26, 21 sealingly engage the workpiece 2, pressure switch 1 is ultimately actuated to simultaneously start timer TR2 and energize solenoid 71 which results in bore portions 2&1, 21a and the hollow workpiece 2 becoming filled with fluid. When the hollow portions of seals 28, 21 and Workpiece 2 have been completely filled with fluid, the normally open contacts 74 of timer TR-2 become closed. When this occurs, the operator can initiate operation of the forming cylinders 38, 39 and cause pistons 40, 41 to ad- Vance simultaneously as before by pressing the Form On button, thereby energizing relay (ER-7 which will then remain energized by means of a holding circuit which includes normally open contacts 104 of relay CR-7 and which is parallel-connected with the Form On" button. As before, this causes pistons 40, 41 to advance together with their respective rod ends 41, 43 thereby first simultaneously closing 01f ports 26, 27, thus capping and simultaneously applying pressure to the fluid trapped witln'n the hollow bores 29a, 21a and workpiece 2 upon continued advance movement of the pistons. As noted heretofore, as pistons 49, 41 continue to advance the pressure of the trapped fluid is increased as well as the pressure in conduit 49 which ultimately results in the actuation of pressure switch PS-Z thereby causing its contacts 80, 81 to complete a circuit through line 82 and energize relay CR-S. As before, when CR- isenergized, this results in relays CR-4 and (JR-6 becoming de-energized.

Also, when relay CR-S has been energized, the pistons 4t),

41 can be retracted to their initial positions by the operator pressing the Form Return button to energize relay CR'8.

Next, the Seals Out but-ton is closed thereby energizing relay (ZR-9 since the normally open contacts 105 of relay CR-l are then closed which, as before, causes seals 20, 21 to be retracted away from the workpiece and returned to their initial positions. The operator then depresses the Mold Up button which, together with ncrmallyclcsed contacts 89 of relay CR4 and normally open contacts 106 energizes relay (JR-3 thereby retracting press 6 and opening die 3. At any time after an operating cycle has been initiated and prior to its completion, by closing the Emer. Rev. button to energize relay CR-S, all components'will be returned to their initial positions automatically if the selector switch is in the automatic position, or the control system is placed in condition whereby an operator can return one element at a time to its initial position by closing the Form Re- 7 turn, Seals Out, and Mold Up buttons individually, as noted above. I Thus it will be'seen that the invention provides greatly simplified apparatus and control through the application of opposed mechanical forces and balanced hydraulic pressures whereby hollow objects may be formed without elaborate means for controlling the feeding of the material of an object being formed in correlation with hydraulic pressures utilized in the forming process. 7

Having thus described what is presently considered to be a preferred embodiment of the invention, it is to be understood that such description is intended by way of example only and is not intended to be limiting. For example, while it is considered advantageous to employ a pump, such as pump 28, for filling the hollow portions of the respective seals and the workpiece, the invention is not necessarily restricted thereto. If desired, fluid could be supplied to said hollow portions of the seals and to the workpiece by means of a gravity feeding system connected to a suitable fluid reservoir. Also, if desired, either or both pressure switches PS-l and PS2 might have substitu-ted therefor another type of condition responsive device such as, for example, a position sensing device such as a limit switch or micro-switch operable in response to a position of a movable member such as either or both of seals 20, 21 and/or either or both of pistons 40, 41.-

While particular embodiments have been illustrated and described, it will be apparent to those skilled in the Having thus described my invention, what claim as 6 new and useful and desire to secure by United States 7 Letters Patent is;

1. Apparatus for forming a hollow member comprising a diehaving a cavity therein and having relatively movable portions, said die portions having a pair of passageways each providing access to the opposite ends of a hol- 'low member within said die cavit means for opening and closing said die portions, a pair of hollow tubular. seals each having a distal end portion adapted to sealingly engage an open end of said hollow member, means for causing said seals to advance from an initial rearward position to a second forward position with said distal end portions sealingly engaging the opposite ends of said member and for retracting said seals to said initial position,' means including a fluid conduit opening into the initial positions. 7

a 8' hollows of said seals for filling with fluid the hollows of said seals and the hollow member when said distal end portions are in sealing engagement with the opposite ends of the hollow member, means including a reciprocable member disposed within the hollow of each said seals and movable from behind to in front of said opening for consecutively closing said opening and thereafter trapping fluid and increasing the pressure of said fluid within said seals and the hollow member to cause said member to conform tothe shape of said cavity, and means for actuating the seal retracting means and the die opening means.

2. Apparatus for forming a hollow member comprising a die having a cavity therein and having relatively movable portions, each having .a pair of passageways each providing access to the opposite ends of a hollow member Within said die cavity, means for opening and closing said die portions, a pair of hollow tubular, seals each having a distal end portion adapted to sealingly engage an open end of said hollow member, means operable in response to the closing of said die portions for causing said seals to advance from a rearward initial position to a second forward position in which said distal end portions sealingly engage the opposite ends of said member, means including a fluid conduit opening into the hollows of said seals for filling with fluid the hollow seals and the hollow member when said distal end portions are in sealing engagement with the opposite ends of the hollow member, pressure intensifier means including a movable member disposed within the hollow of each said seals and movable from behind to in front of said opening for consecutively closing said opening and thereafter trapping fluid increasing the pressure of said fluid within said seals and the hollow member upon movement of the movable member to cause said hollow member to conform to the shape of said cavity, means for simultaneously moving each of said movable members, and means for returning said seals to said initial position and actuating the die opening means.

3. Apparatus for forming a hollow member comprising a die having a cavity therein and having relatively movable portions, eachhaving a pair' of passagewayseach providing access to the opposite ends of a hollow member within said die cavity, means for opening and closing said die portions, a pair of hollow tubular seals each having a a distal end portion adapted to sealingly engage an open end of said hollow member, hydraulic means for causing said seals to advance from an initial rearward position to a second forward position in which said distal end,

portions sealingly engage the opposite ends of said member, means including a fluid conduit opening into the hollows of said seals for filling with fluid the hollow-seals and the hollow member when saiddistal end portions are in sealing engagement with the opposite ends of the hollow member, means including a movable member disposed within the hollow of each said seal and movable from behind to in front of said opening for consecutively. closing said opening and thereafter trapping fluid and increasing the pressure of said fluid within said seals and the hollow member upon movement of said movable member to cause the hollow member to conformto the shape of said cavity, hydraulic means for causing movement of the movable member, and means for returning said seals and said'movable members to 4. Apparatus for forming a hollow member comprising a die having a cavity therein and having relatively movable pcrtions, said die portions having a pair of passageways each providing access to the opposite ends of a hollow, member within said die cavity, means for opening and closing said die portions, a pair of oppositely disposed hollow tubular seals each having a distal end portion 1 adapted to sealingly engage an open end of said hollow member, hydraulic means for causing each of said seals 7 to advance from an initial rearward position to a second forward position in which said distal end portions sealingtheir respective ly engage the opposite ends of said member, means including a fluid conduit opening into said hollow seals for filling with fluid the hollow seals and the hollow member when said seals are in said second position, means including a reciprocable member disposed within the hollow of each said seals and movable from behind to in front of said opening for consecutively closing said opening and thereafter trapping fluid and increasing the pressure of said fluid within said seals and the hollow member to cause said member to conform to the shape of said cavity, hydraulic means for simultaneously moving each of said reciprocable members in a direction corresponding to that of its associated seal in moving to said second position, and means for returning the seals and the reciprocable members to their respective initial positions.

5. Apparatus for forming a hollow member comprising a die having a cavity therein and having relatively movable portions, said die having at least one fluid pas sageway providing access to one end of a hollow member located within said die cavity, means for opening and closing said die portions, at least one hollow tubular seal having a distal end portion adapted to sealingly engage an open end of said hollow member, means for causing said seal to advance from an initial rearward position to a second forward position with said distal end portion sealingly engaging the end of said member and for retracting said seal to said initial position, means including a fluid conduit opening into said tubular seal for filling with fluid the hollow of said seal and the hollow member when said distal end portion is in sealing engagement with the end of the hollow member, means including a reciprocal member disposed within the hollow of said seal and movable from behind to in front of said opening for consecutively closing said opening and thereafter trapping fluid and increasing the pressure of said fluid within said seal and the hollow member to cause said member to conform to the shape of said cavity, and means for actuating theseal retracting means and the die opening means.

References Cited in the file of this patent UNITED STATES PATENTS Leuthesser et a1 July 19, 1955 2,902,962 Garvin Sept. 8, 1959 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No; 3,151,590 October 6 1964 Milton M. Garvin It is hereby certified that error appears in the above numbered pat-- ent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 21, for "a rearward initial" readan initial rearward line 32 after "fluid" first occurrence, insert and same column 8 line 54, for "seal" read seals Signed and sealed this 16th day of February 1965 v (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer 4 Commissioner of Patents 

1. APPARATUS FOR FORMING A HOLLOW MEMBER COMPRISING A DIE HAVING A CAVITY THEREIN AND HAVING RELATIVELY MOVABLE PORTIONS, SAID DIE PORTINS HAVING A PAIR OF PASSAGEWAYS EACH PROVIDING ACCESS TO THE OPPOSITE ENDS OF A HOLLOW MEMBER WITHIN SAID DIE CAVITY, MEANS FOR OPENING AND CLOSING SAID DIE PORTIONS, A PAIR OF HOLLOW TUBULAR SEALS EACH HAVING A DISTAL END PORTION ADAPTED TO SEALINGLY ENGAGE AN OPEN END OF SAID HOLLOW MEMBER, MEANS FOR CAUSING SAID SEALS TO ADVANCE FROM AN INITIAL REARWARD POSITION TO A SECOND FORWARD POSITION WITH SAID DISTAL END PORTIONS SEALINGLY ENGAGING THE OPPOSITE ENDS OF SAID MEMBER AND FOR RETRACING SAID SEALS TO SAID INITIAL POSITION, MEANS INCLUDING A FLUID CONDUIT OPENING INTO THE HOLLOWS OF SAID SEALS FOR FILLING WITH FLUID THE HOLLOWS OF SAID SEALS AND THE HOLLOW MEMBER WHEN SAID DISTAL END PORTIONS ARE IN SEALING ENGAGEMENT WITH THE OPPOSITE ENDS OF THE HOLLOW MEMBER, MEANS INCLUDING A RECIPROCABLE MEMBER DISPOSED WITHIN THE HOLLOW OF EACH SAID SEALS AND MOVABLE FROM BEHIND TO IN FRONT OF SAID OPENING FOR CONSECUTIVELY CLOSING SAID OPENING AND THEREAFTER TRAPPING FLUID AND INCREASING THE PRESSURE OF SAID FLUID WITHIN SAID SEALS AND THE HOLLOW MEMBER TO CAUSE SAID MEMBER TO CONFORM TO THE SHAPE OF SAID CAVITY, AND MEANS FOR ACTUATING THE SEAL RETRACTING MEANS AND THE DIE OPENING MEANS. 